tamerakshar
Full Member level 1
analog vs digital technology
1-Analog:
electronic transmission accomplished by adding signals of varying frequency or amplitude to carrier waves of a given frequency of alternating electromagnetic current.Broadcast and phone transmission have conventionally used analog technology.
Analog also connotes any fluctuating, evolving, or continually changing process. Analog is usually represented as a series of sine waves. The term
originated because the modulation of the carrier wave is analogous to the fluctuations of the voice itself.
One of the distinctive character betweent analog and digital wireless technology is their modulation method.For analog system, we usually use FM,AM, DSB,SSB and VSB techniques.
FM: Frequency Modulation. It's the most popular analog modulation technique. In FM, the amplitude of the modulated carrier signal is kept constant while its frequency is varied by the modulating message signal.Thus,FM signals have all their information in the phase or quency of the carrier.
AM: Amplitude Modulation. There is a linear relationship between the quality of the received signal and the power of the received signal since AM signals superimpose the exact relative amplitudes of the modulating signal onto the carrier.Thus,AM signals have all their information in the amplitude of the carrier.
DSB: Double Sideband AM. This kind of AM removes the carrier spectrum from total signals to increase modulation efficiency.
SSB: Single Sideband AM. Since both sideband of an AM signal carry the same information,it is possible to remove one of them without losing any information.SSB AM transmit only one of the sideband about the carrier,and hence occupy only half the bandwidth of conventional AM systems.
2-Digital:
Digital describes electronic technology that generates, stores, and processes data in terms of two states: positive and non-positive. Positive is expressed or represented by the number 1 and non-positive by the number 0. Thus, data transmitted or stored with digital technology is expressed as a string of 0's and 1's. Each of these state digits is referred to as a bit (and a string of bits that a computer can address individually as a group is a byte).
The modulation techniques of digital wireless signal are more complicated than those of analog signals.Here I just give you a list of them, for
further information please check the reference.
Linear Modulation Techniques:
BPSK : Binary Phase Shift Keying
DPSK : Differential Phase Shift Keying
QPSK : Quadrature Phase Shift Keying
Constant Envelope Modulation Techniques:
BFSK : Binary Frequency Shift Keying
MSK : Minimum Shift Keying
GMSK : Gaussian Minimum Shift Keying
Combined Linear and Constant Envelope Modulation Techniques:
MPSK : M-ary Phase Shift Keying
QAM : M-ary Quadrature Amplitude Modulation
MFSK : M-ary Frequency Shift Keying
Spread Spectrum Modulation Techniques:
DS-SS : Direct Sequence Spread Spectrum
FH-SS : Frequency Hopped Spread Spectrum
1-Analog:
electronic transmission accomplished by adding signals of varying frequency or amplitude to carrier waves of a given frequency of alternating electromagnetic current.Broadcast and phone transmission have conventionally used analog technology.
Analog also connotes any fluctuating, evolving, or continually changing process. Analog is usually represented as a series of sine waves. The term
originated because the modulation of the carrier wave is analogous to the fluctuations of the voice itself.
One of the distinctive character betweent analog and digital wireless technology is their modulation method.For analog system, we usually use FM,AM, DSB,SSB and VSB techniques.
FM: Frequency Modulation. It's the most popular analog modulation technique. In FM, the amplitude of the modulated carrier signal is kept constant while its frequency is varied by the modulating message signal.Thus,FM signals have all their information in the phase or quency of the carrier.
AM: Amplitude Modulation. There is a linear relationship between the quality of the received signal and the power of the received signal since AM signals superimpose the exact relative amplitudes of the modulating signal onto the carrier.Thus,AM signals have all their information in the amplitude of the carrier.
DSB: Double Sideband AM. This kind of AM removes the carrier spectrum from total signals to increase modulation efficiency.
SSB: Single Sideband AM. Since both sideband of an AM signal carry the same information,it is possible to remove one of them without losing any information.SSB AM transmit only one of the sideband about the carrier,and hence occupy only half the bandwidth of conventional AM systems.
2-Digital:
Digital describes electronic technology that generates, stores, and processes data in terms of two states: positive and non-positive. Positive is expressed or represented by the number 1 and non-positive by the number 0. Thus, data transmitted or stored with digital technology is expressed as a string of 0's and 1's. Each of these state digits is referred to as a bit (and a string of bits that a computer can address individually as a group is a byte).
The modulation techniques of digital wireless signal are more complicated than those of analog signals.Here I just give you a list of them, for
further information please check the reference.
Linear Modulation Techniques:
BPSK : Binary Phase Shift Keying
DPSK : Differential Phase Shift Keying
QPSK : Quadrature Phase Shift Keying
Constant Envelope Modulation Techniques:
BFSK : Binary Frequency Shift Keying
MSK : Minimum Shift Keying
GMSK : Gaussian Minimum Shift Keying
Combined Linear and Constant Envelope Modulation Techniques:
MPSK : M-ary Phase Shift Keying
QAM : M-ary Quadrature Amplitude Modulation
MFSK : M-ary Frequency Shift Keying
Spread Spectrum Modulation Techniques:
DS-SS : Direct Sequence Spread Spectrum
FH-SS : Frequency Hopped Spread Spectrum
